1. Field of the Invention
The present invention relates to an apparatus for treating a thin film and a method of treating a thin film.
2. Background of the Related Art
Until recently, display devices have typically used cathode-ray tubes (CRTs). Presently, much effort is being expended to study and develop various types of flat panel displays, such as liquid crystal display (LCD) devices, plasma display panels (PDPs), field emission displays, and electro-luminescence displays (ELDs), as a substitute for CRTs.
These flat panel displays have a light emitting layer or a light polarizing layer on at least one transparent substrate. Recently, an active matrix type flat panel display, where a plurality of thin film transistors (TFTs) are arranged in a matrix manner, has become widely used due to high resolution and high ability of displaying moving images.
The flat panel display includes multiple thin films. Accordingly, the flat panel display is fabricated through the repetition of a thin film-depositing process, a photolithography process and a thin film-etching process. Also, when a thin film pattern formed through such the processes has defects such as open circuits and short circuits, a process for repairing such the defects of the thin film pattern is conducted.
A thin film-treating process such as a depositing process, an etching process and a repairing process is conducted in a chamber type thin film-treating apparatus having an airtight reaction area. However, large sized substrates are problematic for the chamber type apparatus. In other words, as a size of the flat panel display recently has increased, a size of the chamber also increases in accordance to a size of the substrate. In particular, the flat panel display recently has used a substrate having a size of about square meters (m2). Accordingly, the space occupied by the chamber type apparatus increases.
To solve these problems, instead of the chamber type apparatus requiring a large-sized airtight reaction space, a gas shield type thin film-treating apparatus for treating a part of a substrate under atmospheric condition is suggested.
FIG. 1 is a cross-sectional view of a gas shield type thin film-treating apparatus according to the related art.
As shown in FIG. 1, a gas shield type thin film-treating apparatus uses laser-induced chemical vapor deposition method. In other words, thin film treatment is conducted by photolysis using a light to irradiate a part of a substrate 2 and a reaction gas supplied to the irradiated part of the substrate 2 under atmospheric pressure.
The gas shield type apparatus includes a stage 10 where the substrate 2 is placed, a gas shield 20 over the stage 10, and an energy source 40 over the gas shield 20.
The stage 10 moves up/down and left/right i.e., horizontally and vertically, by using an operating assembly (not shown). The gas shield 20 has a retention space 22, which is open up and down, disposed at a center portion of the gas shield 20 corresponding to the energy source 40. The upper open portion of the retention space 22 is shielded by a transparent window 24. A laser beam “L” irradiates a part of the substrate 2 through the transparent window 24 and the retention space 22. A gas supply path 26 is formed in the gas shield 20 and connected to the retention space 22 to supply the reaction gas. The gas supply path 26 is connected to a gas supplier 50 through a gas supply pipe 52. A plurality of exhaust grooves 28 and 32 are formed at a rear surface of the gas shield 20 facing the substrate 2 to exhaust the residual reaction gas on the substrate 2. Gas exhaust paths 30 and 34 are formed in the gas shied 20 and connected to the corresponding exhaust grooves 28 and 32. Also, the gas exhaust paths 30 and 34 are connected to a pressure adjusting device 54 through a gas exhaust pipe 56. The energy source 40 generates light such as a laser beam “L”. The laser beam “L” passes through the transparent window 24 and the retention space 22 and is focused on the part of the substrate 2.
The substrate 2 is placed on the stage 10, and the stage 10 moves to align the energy source 40 and the gas shield 20 with the substrate 2. Then, the laser beam “L” from the energy source 40 is focused on the part of the substrate 2, and the reaction gas is supplied to the retention space 22 through the gas supply pipe 52 and the gas supply path 26 and flows into the focused part of the substrate 2. The reaction gas is activated by the laser beam “L” at the focused part of the substrate 2, and thus a thin film treatment such as depositing and etching is conducted at the part of the substrate 2. During the thin film treatment, the gas exhaust paths 30 and 34 and the gas exhaust pipe 56 are under negative pressure by the pressure adjusting device 54 to prevent the poisonous reaction gas and a gaseous by-product from leaking outside. Accordingly, the residual reaction gas and the gaseous by-product are continuously exhausted through the exhaust grooves 28 and 32.
Through the above-explained processes, the related art gas shield type apparatus conducts the thin film treatment for the part of the substrate under atmospheric condition. However, the related art gas shield type apparatus has some problems.
Since the thin film treatment is conducted under atmospheric pressure, a large amount of reaction gas is wasted and is not used for the thin film treatment. In other words, since gas supplying and gas exhausting are conducted at the same time, a large amount of reaction gas is wasted and is not used for the thin film treatment. Accordingly, the rate and efficiency of the thin film treatment are reduced. Further, the moving speed of the stage is limited. For example, when a repairing process to connect an open-circuited thin film pattern is conducted, the irradiating range of the laser beam, i.e. the focusing area is about 300 μm2 while the moving speed of the stage is about 3 to 10 μm/sec. Accordingly, the total process time for one substrate, i.e. a total around cycle time (TACT), is large.
Further, a supplying pressure and an exhausting pressure of the reaction gas are different according to positions of the substrate, and thus uniformity of the thin film treatment is reduced. In other words, in the related art gas shield type apparatus, since the thin film-treatment is conducted under atmospheric pressure, maintaining constant pressure for supplying and exhausting the reaction gas is problematic compared with the chamber type thin film-treating apparatus. In particular, since distances from the respective exhaust grooves 28 and 32 to the pressure adjusting device 54 are different, pressures for exhausting the reaction gas are different according to positions of the exhaust grooves. Accordingly, uniformity of the thin film treatment is reduced.
Further, the related art gas shield type apparatus occupies a large area. In other words, the gas supply path 26 is disposed at a height different from the gas exhaust paths 30 and 34 in the gas shield 20, and thus the gas shield 20 has an indispensable thickness to some degree. Also, the exhaust grooves 28 and 32 include a first groove 28 disposed around the retention space 22 and a second groove 32 disposed around the first groove 28, and thus the gas exhaust paths 30 and 34 are independent from each other. Accordingly, the gas shield 20 has large thickness and volume.
Further, due to a large size of the gas shield 20, the stage 10 is movable in order to reduce the generation of impurities such as particles and to simplify the operation. Accordingly, the occupation area used by the apparatus is about two times the size of the substrate 2.
Further, the reaction gas in the gas supply path 26 and the residual reaction gas in the gas exhaust path 30 and 34 are cooled or hardened in the corresponding gas paths 26, 30 and 34. Accordingly, the cooled or hardened reaction gas acts as particles and thus contaminates the substrate 2 or blocks the gas paths 26, 30 and 34.